This invention relates to breeding of crop plants. In particular, it relates to producing hybrid wheat seeds on a commercial scale.
Controlled cross pollination of plants has been utilized by plant breeders for production of hybrid strains of plants which combine desirable qualities of the original parents. The desired first generation hybrid plants produced by controlled cross pollination have uniform qualities, including the size, height and genetic composition of plant products of economic importance. Since the progenies of the first generation hybrid plants have uneven physical characteristics and differ widely in genetic composition, in order to retain the advantages of a uniform, high quality hybrid crop, the farmer must be supplied with hybrid seeds each time he plants his crop.
One approach for controlling cross pollination of plants is to use cytoplasmic male sterility. In onion, for example, cytoplasmic male sterility can be introduced into one inbred line by backcrossing a fertile line which possesses some desired characteristics into plants that have cytoplasmic male sterility. The inbred male-sterile line is then planted in alternate strips with a male fertile inbred line, in an isolated field. The cross pollination produces, on the male sterile plants, hybrid onion seeds for a commercial crop.
The cytoplasmic male sterility was also utilized in production of hybrid corn seeds as described in the U.S. Pat. No. 2,753,663. Unlike in onion where the vegetative plant parts are of economic value, in corn it is the seed that is harvested. Since male sterile corn plants produce no seeds, a hybrid produced in accordance with a method for production of onion hybrids would be useless to the farmer. The problem was solved by utilizing a fertility restoring plant for the final cross resulting in a hybrid corn seed.
The researchers have attempted to apply the method disclosed in U.S. Pat. No. 2,753,663 to wheat; however, despite continuing efforts, commercially satisfactory restorer plants have not been found. The development of a satisfactory hybrid wheat system has been complicated by the fact that the wheat flower is bisexual and since in wheat the anthers are in the florets, the plants are practically always self pollinated. The location of the wheat anthers inside the florets and the fact that pollen is shed before flowers open makes introduction of male sterility in wheat by physical means (such as manual emasculation) commercially unfeasible. A genetic system, based on cytoplasmic sterility, appears to be the only feasible way for commercial production of hybrid wheat seeds.
The invention satisfies the long felt need for a relatively simple, commercially feasible method of producing hybrid wheat seeds.
Thus one object of the invention is to provide a genetic method for a production of hybrid wheat seeds.
Another object of the invention is to provide a commercially feasible and reliable method for production of hybrid wheat seeds.
A further object of the invention is to use cytoplasmic genetic sterility to produce hybrid wheat seeds having desirable properties.
Still another object of the invention is to provide a genetic method for producing hybrid wheat seeds, which does not require special development of the restorer line and in which conventional common wheat cultivars can be used as the restorer line.
Other objects of the invention will become apparent to those skilled in the art upon studying this disclosure.